They found that in certain concentrations, the compounds effectively slowed the growth of the bacteria.

It's activated by a certain concentration of C02 in the blood.

Some of these substances can only remain dissolved in water at certain concentrations.

It's continuously monitored and drawn off to keep the levels below a certain concentration.

These bacteria can grow within a host without harming it, until they reach a certain concentration.

Studies have linked them to reproductive and neurological risks at certain concentrations or higher.

In addition to the major, students also specify certain concentrations, either a subject interest or a regional focus.

The humidity should be above a certain concentration, too.

There has to be a certain concentration of the black iron for it to throw off white fire.

We like company, not crowding - but a certain concentration is necessary for ideal efficiency.